Somebody once told me that Knuffel get more experience from digging outside of their element, so I started raising them outside of their element. And I've been doing that for years, so why stop? Sometimes, there's some sort of "logic" in it - for example, Darkness Gen 21 reminds me of drow, dark elves, this kind of creature; dark elves in Elder Scroll games can naturally set themselves on fire, therefore, I'm raising my Knuff in fire element

But it's usually less complicated, like "the sun is in the sky" (Light Gen 5 - air) or "you need sun to make a rainbow" (St. Patrick Knuff - light)